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Add volume under false bottom setting

dunleav1

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it would be great to have a volume under false bottom setting, so you can calculate you grist ratio correctly.
 
I've added this as an optional adjustment in BeerSmith 2.0.  You can (if you wish) have it add your lauter/tun losses volume to the first step of the mash to compensate for losses.

Brad
 
Brad,

I thought that option was for this, and I was very excited when I saw it, but I am not sure it is working correctly.

I use a false bottom in my mash tun, and I need to add 4 litres of water to the tun before it just covers the false bottom. In addition to this, the tun itself has a dead space of 0.2L. I therefore put in the dead space in the equipment settings as 4.2L, and I tick the box adjust mash volume for dead space...

This all works up to a point - beersmith calculates the extra 4 litres of mash water needed and adds this to the initial volume. However, it still thinks I will leave 4.2L behind in the tun, and as I batch sparge, it adds an extra 2L to each batch in order to compensate for this, giving me an excess of 4L in the boiler (since I will get back that 4L under the false bottom on the first batch run-off).

At the moment, I work around this by just adding my dead space as 0.2L and leave the adjust mash volume for dead space unticked. I then choose my mash as normal in the recipe creation, and I edit the mash step by adding an extra 4L to the volume beersmith calculates.  Beersmith then correctly deducts 4L from the 1st batch topup calculation and all continues from normal..

It would be good if there was an automatic way to do this though, as it is easy to overlook manually editing the batch stage.

Hope this makes sense!

Grahame
 
I've just found this post as I'm having the same issue.  Any movement on this guys?

Cheers

Steve
 
Same issue. I have a direct fire mash tun that takes 1.2 gal to cover the false bottom. I need this extra thermal mass to correctly compute a strike temperature, but my dead space when draining is .2 gal or less. I use Grahame's method as a work around, but would prefer a tab I can click and enter this volume.

 
Hi,
  I'm having a bit of trouble following this - obviously the extra water is added to the mash.

  I'm assuming you want extra water added to the mash but not treated as a loss when the tun is drained??

Brad
 
Exactly. As it appears, the wort below the false bottom is treated as a loss. Where as the only loss I have is a small amount (maybe a pint vs. 1.2 gal) that I can't drain due to construction of the mash tun. For recipe formulation, I use 1.25 lb/qt grain to water. However, for strike calculations I have to add the water below the false bottom or strike temps are too high. This ultimately gives me about  a 1.45 ratio. The mash above the false bottom behaves like a 1.25 ratio.
 
Agreed.  This is a personal pain and should be same for everyone using a PolarWare pot with false bottom.  The "under bottom" amount also won't stir in at all, so mashes are stickier than the ratio would suggest.  But the un-stirrable water is there adding heat.  Took me a long time to figure out my "house rules." 
 
[cue angels singing]

I'm so happy I found this thread as I was about to start my own.  Here is my situation for further clarification and maybe some insight as to how to implement.

My setup
10 gallon round cooler with false bottom.  The false bottom is positioned above the valve which also has a dip tube attached.  The volume below the false bottom (aka "slack space") is 1 gallon.  The true dead space - the volume my dip tube doesn't pick up - is .25 gallons. 

The problem
Putting in .25 as my dead space throws off my mashing in water volume making my mash too thick since a full one gallon isn't in contact with the grain.  Putting in 1 gallon throws off my efficiency and other estimated volume calculations since I truly recover all but .25 gallons of the wort.

My current work around
When mashing in, I add 1 gallon to my mash water volume.  The extra 1 gallon sits below the false bottom and so the mash thickness ratio above the false bottom is correct.  After the mash, I drain to the boil kettle leaving .25 gallons in my dead space.  When sparging I add .75 gallons off wort back into the mash tun to fill up the space below the false bottom (aka slack space).  I then add my sparge water and proceed as normal. 

What I would like to see
To Brad's suggestion, yes, I'd like to see the extra water added to the mash in volume, but not treated as a loss.  When sparging (batch sparging at least) it should add in the extra water (or wort) to the sparge volume.  Extra water will dilute the expected runnings whereas added wort (I think) would make the runnings gravity closer to what was expected.
 
I'd really like to see this too!  It's very confusing trying to get this right as it is.
 
Brad,

Any update on this?  I feel that using a false bottom is pretty common.  Please advise.  Thanks!

 
Does it make sense to just ignore the amount of water under the false bottom and assume that it mixed with your grist?  Then adjust your grist to water ratio to a point where you are satisfied with it?
 
Any updates on this?  This seems like it'd be easy to add to the calculations... this space definately affects the mash in temperatures/thermo properties, and then the following sparge volumes as you may have 1-2 gallons of wort under the false bottom but only leave behind a cup and that water isn't part of the grist ratio as its below the grain bed...
 
I am also still looking for a way to factor this into my equipment profile. I can manually adjust for the extra volume under the false bottom minus the actual liquid left behind after draining. What I really want is to be able to do is have my equipment profile accurately reflect my setup.
 
Just adding my solution to this problem should anyone else stumble upon this post.

1.) Enter your correct deadspace (the actual water lost to the mash/lauter tun, not the volume under your false bottom) in the "Tun Deadspace" field of the mash profile.
2.) Tick Adjust Mash vol for Deadspace
3.) Enter your desired Water-to-Grain ratio as part of the strike mash step. Note the suggested water to add, and temperature at which to add it.
4.) Use the formula below to calculate a new Water-to-Grain ratio that includes the volume under your false bottom.

New ratio = [Suggested volume (step 3) + Volume under false bottom - Tun Deadspace (step 1)] / weight of grain

5.) Replace your desired Water-to-Grain ratio from step 3 with this new ratio.

The new Water-to-Grain ratio will now ensure that the updated strike volume fills the volume under your false bottom, while ensuring the volume above the false bottom that contacts the grains is still your desired ratio from step 3 + that added by ticking "Tun Deadspace". The given sparge volume will be correct, and the infusion temperature will be in the ball park (slightly off as the additional false bottom water is not in contact with grain to cool it). You could simple add all but the false bottom volume at the temperature recorded in step 3 (ignoring the strike temperature given with the new ratio), and the false bottom volume at the desired mash temperature. But I doubt it will really be an issue.

Example:
Batch size - 20.8 L, 60 min boil
7.73kg grain at 22.2 C
Targeted 65 C strike temp
Desired 3 L/kg Water-to-Grain ratio, with 7.75 L absorption
4L under false bottom
1L tun deadspace, 1.9L lost to both trub
4.21L/hour boil-off

Suggested strike volume is 24.2L, hence -
(24.2 + 4 - 1) / 7.73 = 3.52 new Grain-to-Water ratio

Using all the values given to me by beer smith:
New strike volume will be 28.23L at 70.6 degrees C (single infusion, light body, no mashout), with a sparge of 8.34L.
Pre-boil volume = 28.23 + 8.34(sparge) - 1(deadspace) - 7.75(absorption) = 27.82 L
Volume into fermentor = 27.82 - 4.21(evaporation) - 0.94 (shrinkage) - 1.9(trub) = 20.8L
 
Adding to my previous post, I have derived a formula for calculating the temperature of the strike water, given that you are adding more volume to account for the volume under the false bottom, and that this extra liquid does not contact the grains (and therefore does not lose heat to them). This formula also incorporates mash tun thermal losses, just as beersmith does. See attachement and use metric units. Someone may be able to simplify the equation further.

R = desired water to grain ratio (the liquid that will be in contact with the grains above the false bottom, e.g. 2 - 3 L/kg)
mg = weight of the grain
Vf = volume under the false bottom
mt = weight of your mash tun
Vm = mash volume needed (recipe > mash > bottom left)
Vt = volume of your mash tun
ct = heat capacity of your mash tun (see equipment manager, e.g. 0.12 kc/kgK for stainless)
cg = heat capacity of grains (~0.38-0.41 kc/kgK)
T = target mash temperature
Tg = temperature of grains
Tt = temperature of mash tun
Ts = adjusted strike water temperature

 

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I am new to Beersmith but found the inability to account for recovered wort under false bottom my first stumble. Seems to me the space under false bottom really has two components: recovered (used) and unrecovered (lost) wort. The recovered water volume just needs to be subtracted from sparge volume. Should be quite simple to handle programatically...maybe the devil is in the details. Unless I am unique, I suspect that many brewers have MLT's with a sizable space under false bottom.
 
When setting up your equipment profile in BeerSmith, it has an input for 'Mash Tun Dead Space' which is the volume in your mash tun which you cannot drain out during lautering.  I believe you may be confusing this 'mash tun dead space' with the total volume under your false bottom.

BeerSmith does not measure or account for any recovered water under your false bottom.  The amount is usually taken into account when determining how much water to add for initial strike water.

In the formula desitter came up with, he is assuming that the water under the false bottom does not lose heat to the grains, and this is false.  Even though it does not contact the grains directly (assuming that you add the water first and then the grains), the temperature will equalize in your mash tun.  Most people help this along by stirring as they add the grains into the mash tun, which will create an exchange above and below the false bottom.
 
Oginme said:
When setting up your equipment profile in BeerSmith, it has an input for 'Mash Tun Dead Space' which is the volume in your mash tun which you cannot drain out during lautering.  I believe you may be confusing this 'mash tun dead space' with the total volume under your false bottom.

BeerSmith does not measure or account for any recovered water under your false bottom.  The amount is usually taken into account when determining how much water to add for initial strike water.

That is my point exactly and I see it as a limitation in the software. Please temper my comments with my "newbie" status! An option for recovered water under false bottom should be considered in equipment setup. This will get strike (above and below false bottom) and sparge volumes correct.
 
I understand where you are coming from.  The total water needed is the total water needed and it does not matter how much is below the false bottom as long as it is drained in the end.  While I do mostly BIAB brewing, I do have a mash tun with a false bottom.  My dead space is .5 liters and I have approximately 1.25 liters below the screen which is always recovered.  For an average gravity batch of 20 liters at 1.050 gravity, I need approximately 31 total liters of water (0.5 liters to dead space, 3 liters to grain absorption,  6.5 liters to boil off, 1 liters left in kettle, 20 liters in carboy).  This does not change if I do not have the water between the bottom of the screen and dead space.  I still have the same total water demand.

In my profile, I split the water for mash and sparge to get approximately equal runnings from both, centered around a typical recipe.  Thus my strike water is 0.5 liters for the dead space, 3 liters for grain absorption plus half of the remaining water (13.75 liters).  For a 6 kg grain bill this gives me a mash in at 2.875 liters/kg of grain (1.4 qts/lb).  If I omit the recovered water, my actual water in contact with the grain to grain ratio 2.8 liters per kg or 1.34 qts/lb.  Because this is centered on the majority of my brews, the actual ratio of water in contact with the grain will vary slightly, but will always be consistent. 

As the grain bill increases, the actual water to grain ratio will increase slightly, which helps to maintain my efficiency fairly consistent.  As the grain bill drops, the water to grain ratio will drop slightly to 1.25 qts/lb of grain, still in a comfortable place. 

Personally, I don't see this as a limitation, but rather a constant which is easily managed with the mash profile.

 
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